ER+ patients should avoid phytoestrogens?

Question fromAnn:
Phytoestrogens (plant estrogens like soy) are not the same as human estrogen. Why should ER-positive breast cancer patients avoid phytoestrogens?

Answers -Mindy Goldman, M.D.
Phytoestrogens and soy are natural forms of estrogen. In some countries where the average daily intake of soy is much higher than those in the U.S., such as the Asian countries, the incidence of estrogen-receptor-positive cancers like breast cancer is actually lower. So some people think that soy and phytoestrogens may be beneficial and help protect against cancer.

Other people are concerned that, because soy is a form of estrogen, it may be dangerous for someone who already has an estrogen-receptor-positive breast cancer. The bottom line with soy is that, similar to the herbal products, we need more quality studies and randomized controlled trials looking at its safety and efficacy.

What the oncologists in our breast cancer center and I have adopted is that if someone with an estrogen-receptor-positive tumor wants to use dietary forms of soy, such as soy milk, tofu, tempeh, we're comfortable with that. But we discourage people from going to the health food store and picking up soy phytoestrogen tablets or other phytoestrogens.

I have found that soy is frequently beneficial, particularly for women who notice hot flashes at night or night sweats. I often have them drink eight to ten ounces of soy milk before bed.

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